The quality of many products sold to consumers has a range of environmental conditions, and the value of a product depreciates due to spoilage, etc. under improper temperature conditions that are beyond the range.
For example, a food spoils when it is not stored and distributed within a proper temperature range, and when a product that requires refrigerated distribution, such as a prepared medicine, is exposed to an environment outside an allowable temperature range, it cannot perform or deliver its expected function. Moreover, when a food that is susceptible to microbial contamination is exposed to undesirable temperatures, it cannot be eaten due to microbial growth.
Therefore, when a product is made of perishable material, it is important to determine the lifespan of the material and determine whether the product can be currently used.
To this end, an expiration date has been marked on a packing material so far, but it is impossible to accurately determine the state of the product only with the marked expiration date. In particular, the state of a perishable product generally has a great correlation with time and temperature conditions.
Moreover, it is possible to easily change the expiration date, and thus it is insufficient to give enough confidence to a consumer that consumes the corresponding product.
Meanwhile, a Quick Response (QR) code, which was developed by Denso Wave Inc. in 1994, is a matrix-type two-dimensional code in which the same number of small square dots is arranged lengthwise and breadth-wise and includes various versions ranging from 21 to 177 rows/columns (Version 40).
Furthermore, unlike a barcode, the QR code has finder patterns located at three corners of the matrix and thus is readable in any direction of 360 degrees. The largest QR code (Version 40) can record information of up to 23,648 bits. The QR code is printed on a signboard or newspaper to deliver information.
So far, there is no method available to automatically track and identify a product that is exposed to an undesirable environment from the time when the product is manufactured or packed until it reaches its final destination.
Therefore, there is a need to provide a method for detecting any environmental change in temperature and identifying a product with reliability or usefulness that is considered as being potentially dangerous.